Mariner s compass



E. S. RITCHIE.

Mariners Compasses.

Ptented Sept. .9, 1862.

wnfssfa UNITED STATES PATENT OFFICE.

EDWARD S. RITCHIE, OF BROOKLINE, MASSACHUSETTS.

MARINERS COMPASS.

Specification of Letters Patent No. 36,422, dated September 9, 1862.

' Mariners Compasses; and I do hereby declare the same to be fullydescribed in the following specification and represented in theaccompanying drawings, o-f which- Figure l, is a to-p plan view, andFig. 2, a vertical section of a mariners compass, provided with myinvention, which has reference to those marine Compasses whose cards areimmersed in a liquid contained within a bowl or case.

The nature of the said invention consists in the arrangement andcombination of an air-vessel with the magnet or with the same and itscard, in a manner and so as not only to encompass the magnet or magnetsand completely insulate the same from the surrounding liquid, but alsoto buoy up the card and magnet or the magnet or magnets, or remove moreor less of the weight thereof fromthe pivot.

My improvement not only prevents the magnet or magnets from'becomingoxidized by the liquid but also operates to lessen in a great degree thefriction and wear of the pivo-t and bearing or cap.

In the drawings, A denotes the liquid reservoir or bowl, whose top (B)is a transparent or glass plate. This reservoir is, when in use tocontain or be filled with a liquid (such as water or a mixture of waterand alcohol) and has a pivo-t, C, projecting upward from the centralpart of its bottom. On this pivot, the compass card, D, is to rest andturn. To t-he underside of the said card, D, (it being a plate of metalsuitably painted or enameled with the usual compass points anddesignating letters) an air-tight vessel or chamber, E, is affixed, themagnet or magnets, Gr, being inclosed therein. The said air-vessel isperforated, so as to permit the pivot ((1,) to pass thro-ugh it tothecap, a, and is provided with a iiange, H, about its center, on its upperside, as shown in the drawings. The cap (a) has a fiange (y,) extendingover the card, and a screw, a, which passes through the card and thesaid flange of the air-vessel, upon which is screwed a hollow frustum ofa cone, H, wh1ch serves to secure the cap and card and the air-vesseltogether. Additional means or screws may be used, when necessary tosecure the card to the air-vessel, such being exhibited at s, s, in thedrawings.

An elevator (1,) is placed below the conic frustum H, for the purpose oflifting the ycap from the pivot when the compass 1s not in use.

The vessel E, should not only be air tight but its buoyant power shouldbe such as to cause it to nearly lift the card D, with the magnet ormagnets, the pressure remaining on the pivot, C, being graduated so asto be of as small an amount as will suffice to cause the card bearingo-r cap to remain in contact with the pivot, and turn thereon with atrifling amount `of friction.

From the above, it will be seen that my invention is not only aprotection to the magnet o-r magnets against oxidation, but, as a meansof buoying nearly all of the weight of the card, and its magnet ormagnets relatively to the point of the pivot o-n which the card issupported and traverses while the compass may be in use.

Vhen the air vessel E, is constructed entirely separate from t-he card,and in other respects substantially as described, we have the means ofapplying my invent-ion to any common liquid compass. The card mayconstitute the cover of the air vessel, and thus malte part of the same.So also the conic frustum may constitute a portion of the air vessel. Iprefer however, that the air vessel, the card and the conic frustum, bemade separate from one another, and be provided with means of connectionas explained.

Having thus described my invention what I claim and desire to secure byLetters Patent, is as follows:

1. I claim the arrangement and combination of the air vessel (E,) withthe magnet or magnets (G).

2. I also claim the combination of the said air vessel and magnet ormagnets with the card (D,) the same being for the purposes as specified.

E. S. RITCHIE. Witnesses:

R. H. EDDY, F. P. HALE, J r.

